The present application relates to a semiconductor structure and a method of forming the same. More particularly, the present application relates to a semiconductor structure including a phase change memory (PCM) cell having a reduced reset current and reduced thermal cross-talk.
Phase change memory (PCM) has emerged as a viable technology to fill the memory application gap between volatile memory and flash memory. PCM is a type of non-volatile random access memory (NVRAM). A NVRAM retains its information when the power is turned off. This is in contrast to dynamic random access memory (DRAM) and static random access memory (SRAM), which both maintain data only for as long as power is applied.
A typically PCM includes a material stack of, and from bottom to top, a bottom electrode, a phase change memory material that exhibits a change in atomic order (from crystalline to amorphous, or vice versa), and a top electrode. The top and bottom electrodes are composed of a conductive material such as, for example, titanium nitride (TiN) or tungsten (W). Such conductive materials are also thermal conductors so heat loss occurs through the top and bottom electrodes of the PCM cell.
Heat loss in a PCM cell causes the following two issues, which are problematic in PCM cells. First, due to heat loss higher current is required to reset a PCM cell and thus higher power consumption is needed. Second, and for a highly scaled PCM cell array in which PCM cells are closely packed, heat from a PCM cell during the reset operation may transfer to adjacent PCM cells, undesirably disturbing the adjacent PCM cells. There is thus a need for providing PCM cells in which heat loss is mitigated thus reducing reset current and thermal cross-talk between adjacent PCM cells.